Ch 18 Magnetism and Electricity Flashcards
what is current electricity.
a steady flow of charge through wires and circuits
what is static electricity
involves electric charge collecting in one place and sometimes suddenly jumping from one place to another
what is one thing that current and static electricity have in common
they both involve the movement of charged particles
what is a conductor and give an example
a substance that allows charged particles to flow through them freely
e.g. conductors
what is an insulator and give examples
a substance that doesn’t allow charged particles to flow through them easy
e.g. rubber and plastic
what are the electrical wires or a circuit made up of
atoms which contain electrons
what is current
the rate of flow of charge per second
what is the si unit for electric current
amperes (A)
how can you measure current
using and ammeter
what are the three effects of electricity
heating, magnetic, chemical
explain how a battery transfers energy to electrons and moves them around the circuit
- battery gives energy to electrons
- huh energy electrons drop through the bulb and convert energy to light
- low energy electrons go back to their battery
what is potential difference
when there’s a point of high electrical energy and a point of low electrical energy in a complete circuit, we say there’s a difference in potential energy between those two points
what is another word for potential difference
voltage
what is the si unit for voltage
volts (V)
what does a voltmeter do
measured the potential difference across a component
what is one “battery” caked on its own
a cell
what is a battery
two or more cells stacked together
what direction is the flow of electric current in a battery
the flow of electric current is from the positive to the negative side of the battery
what are electrodes
two different metals placed in a chemical inside a battery
what is an electrolyte
the chemical that the electrodes are in
what are the two types of battery’s
a primary cell
a secondary cell
what is a primary cell
a battery that can’t be recharged once it’s used
what is a secondary cell
a battery that can be recharged and used again
what is a series
when components are connected in a single loop with each other and the battery
what is a parallel
when components are connected in different branches
what do the voltages across all of the different components sum to in a series
they sum to voltage of the battery in the circuit
what is resistance
a measure of how difficult it is for an electric current to pass through a substance
what is the SI unit for resistance
ohm (the symbol is omega)
how is resistance measured
using and ohmmeter
how do you calculate current
current (A) = voltage (V) divided by restistance
how do you calculate resistance
resistance = voltage divided by current
what is resistance used in
appliances
some devices need resistors in their circuit boards
some devices vary their resistance
what are two types of variable resistor
a rheostat
a potentiometer
what is a resistor
any component that slows down moving charges
how much a resistor slows down the current passing through it depends on:
- length
- temperature
- nature of material
how do you calculate electrical power
electrical power = voltage x current
what is alternating current AC
electrons in the wire are constantly changing direction every fiftieth of a second
what is direct current DC
flows in one direction only
what current do everyday appliances run on
direct current
what is a diode
a component that allows current to flow in one direction only
what is a forward biased diode
when the positive end of the diode is connected to the negative end of the battery. this allows current to flow
what is a reverse biased diode
when the negative end of the diode is connected the to positive end of the battery. no current flows
current only flows when it’s forward biased
yuh
what is a light emitting diode (LED)
a diode that emits light when current flows through it
what is the level of electricity in a live wire and a neutral wire
the live wire has high electrical energy and the neutral wire is low
how does the fuse work in a house circuit
if the appliance is faulty the current in the circuit can become too large. the fuse has a thin piece of wire running through it which is designed to melt if the current goes above the set value. when the fuse wire melts, it breaks the circuit and cuts it the electricity. the earth wire draws a large current through the plug and this helps the fuse wire to melt
